1. Field of the Invention
The invention relates to novel modifications of the compound 2-amino-4-(4-fluorobenzylamino)-1-ethoxy-carbonylaminobenzene of the formula I ##STR2## processes for their preparation and their use in pharmaceutical compositions.
2. Background Information
The compound of the formula I and it preparation is described in the patent DE 42 00 259.
This compound has, for example, anticonvulsive, antipyretic and analgesic activity and can thus be employed in pharmaceutical preparations.
In the crystallization of the compound of the formula I, however, in some cases very different mixed products are obtained with respect to the crystal size and form. Mixtures of crystal modifications are a great problem for pharmaceutical preparations. In particular, in the case of pharmaceutical forms having a high active compound content, physical inhomogeneties have a disadvantageous effect on adherence to constant pharmaceutical production conditions.
On the other hand, considerable variations in the stability, purity and uniformity of the finished product occur, so that the demands on the pharmaceutical quality of an active compound cannot be satisfied.
It is therefore of great interest to prepare the compound of the formula I in homogeneous crystalline form.